The Dale Maley Family Web Site


Glass Clocks

I like using glass on projects based upon how well some of my previous projects turned out (reproduction lamp, and clocks).

I have had difficulty finding existing patterns or designs which utilize glass and wood in smaller size projects.  I did some Google searching and found a clock design that can use a fair sized piece of glass in it:


I used Google Sketchup to come up with a design sort of like this that used glass in the front:

I designed the wood frame to be 1/2 inch wide, to keep it thin looking and to have room for 1/4x1/4" groove to hold the glass.

It is hard to tell if the pattern I saw had a bottom piece of wood or not.  I decided to have a removable piece of bottom wood to hold in the glass when the clock is finished.

I arbitrarily designed the clock to be 3 inches deep, so it could be a mantle clock or a wall-hung clock. Three inches should be enough depth to make it stable from a falling over point of view.

I went to Klock-It web's site, and found they carry round 6 inch diameter faces:

Here is the typical Klock-It movement that is used with these dials:

These movements require a 3/8 inch diameter hole in the material behind the dial. So from a glass cutting point of view, this project gave me 2 new challenges. How to cut a semi-circle at the top of the glass, and how to drill a 3/8" hole in glass.

Let the fun begin


Making the U-Shape from Wood

I decided to laminate 4 thicknesses of 3/4" padauk. This is too thick to bend, given it is 1/2" by 3" cross-section.....based upon my previous work with steam-bending.

I made a pattern by printing out the piece from Google Sketchup:

I first glued up the pieces to make one 3/4" thick U-shape:

  I then planed them slightly to make them flush on both sides. It removes about 1/16" from each side doing the planning operation.  I ended up with a final thickness of 2.5 inches versus my initial target of 3 inches.  This should still work ok.

I cut out the u-shapes on the scroll saw.  I switched to the band-saw because it is much quicker.  Just be sure and leave at least 1/8 extra as you cut the u-shape, to leave material for final sanding.

I then clamped up each of the two pieces first, then clamped all 4 pieces together:


I have been using Nexabond medium set glue on making turned pens and other projects.  I decided to try the fast setting version on this project.

The next step was to drum sand the 4 glued up pieces using my biggest 3 inch drum sander that is also 3 inches high:

Routing the 1/4x1/4 inch groove for the Glass

 Earlier I had seen and bought a bit that is made to put in 1/4x1/4 inch grooves into boxes for the bottom of the box. It eliminates the problem on boxes of the groove showing on the outside of the box.  I decided to try it on this project:

You need to have the bottom piece assembled to keep the router bit from going all the way to the end of the curved pieces.  Since I am going to make the bottom piece removable, I temporarily clamped it in place during the router operation.  I probably could have grooved the bottom piece while it was clamped to the u-shape, but I decided to do it separately,  I used a clamp block to support it during routing:

I used a 1/4" wide sharp chisel to make the ends square in the u-shaped piece to accept the square shaped glass later.  I set the router bit to be 1/4" deep.  There is a smaller bearing to make it 5/16" deep, but I did not use it.

Cutting the Glass

I made a permanent pattern on plywood by gluing on the Google Sketchup print-out:

I verified the fit by temporarily installing it in the u-shaped frame:

I decided to use Kokomo Glass part number 46SPL-g for this project.



Unfortunately, I developed a small crack in the upper part of the glass when I cut the semi-circular top.  It later broke all the way through on me. Before it broke clear through, I went ahead and drilled the 3/8" hole for the clock movement, just to get some experience.

Drilling the 3/8" Dia Hole in Glass

 I have never drilled holes in glass before.  I went to the Fairbury Ace Hardware and they had two types of drill bits. One had a pointed end and package said it was for ceramic tile.  The other style, which I bought, is a diamond coated hollow style bit:

I cut the bottom out of a plastic coffee can to hold a small piece of glass and water. I followed the instructions and used a hand drill, starting to drill at an angle, then shift the angle to 90 degrees.  It worked fine:





Being of a curious nature, I tried drilling a small piece of glass in the drill press. The glass broke.  I suspect the drill press puts too much pressure on the glass compared to a hand-held drill.  So follow the instructions and use a hand drill

To drill the 3/8" hole in the clock glass, I put it on top of a piece of 1x12 pine in my shop kitchen sink, in water:

Clock Glass

Here is the finished glass piece, after I super-glued it back together:



Now I just have to get some more glass and make a new piece to replace this one!

Update on 1st Clock

I had a small piece of red and white glass that looked nice with the red padauk frame, but it was not big enough.  It was Kokomo number 52, pink and opal.

I had to email Kokomo glass and ask what the number was.  By that point, I went ahead and ordered number 118SPLP-G.  A picture of this glass is shown below with the Kokomo opalescent glass part number sticker.

I drilled the 3/8" hole in the glass very slowly with minimal downwards pressure on the diamond coated bit.  I drilled on the rough side as opposed to the smoother side of the glass. I started at 45 degrees and tipped to 90 degrees. I had success!!


Here is the finished Padauk frame glass with the pink Kokomo glass number 118SPLP-G with a gold 6 inch dial..........







I am not a great photographer, so the pictures above do not really do this clock justice.  It really turned out to be a beautiful clock.  The red and white glass really goes well with the red padauk frame.

Removable Bottom Piece

I went back to Ace Hardware to look over their hardware and find some way to make the bottom piece removable.  I decided to use hinges.  I also needed something that had screws less than 1/2" long, side the sides of the U are only 1/2" thick:


Finishing the Padauk Wood Frame

 I did my usual three rounds of 220 grit and gloss polyurethane to finish the frame.

Once I get some new glass I will post the finished clock.


Closing Thoughts on 1st Glass Clock

Drilling the 3/8" hole in the glass turned out to be much easier than I thought it would be using the hollow core diamond coated bit.

Breaking the glass cutting the semi-circle is not surprising. I made a radial line through the arc, and the radial line cracked into the center of the glass.  On future projects, I should do scribe the arc only, and tap it until it breaks.

I did not realize my thickness would shrink from 3 to 2.5 inches due to planning each face. This is ok on this design.



 2nd Glass Clock

I decided to make a 2nd glass clock using red oak for the frame.  Here is all the types of Kokomo glass I have in stock:



I decided to make this clock a wall-mount clock, therefore only use two laminations instead of 4 that I used on the 1st clock.  I also decided to change the process as well:

-band saw front lamination

-drum sand first lamination

-band saw 2nd lamination, leaving 1/8" extra stock

-glue 2 laminations together

-use router bit with follower bearing to made 2nd piece match the profile of the front piece

-finish drum sand OD and ID

On the first clock, I used the drum sander to sand all 4 pieces glued together. It worked, but it took a while and created a lot of dust.  I wanted to see if the router bit pattern method would be easier.

I band-sawed the front piece and took it to the drum sander. Even though I held it carefully because the top section of the U is so fragile, I broke it.  I glued it back together.



I glued on the 2nd piece and was able to use the router bit pattern method ok.  But when I took it to the drum sander to finish sand, it broke also. I glued it back up.

 Here is the flush trim router bit:




Broke the Glass for the 2nd Clock

I got the shape cut out ok, but it broke when I drilled it.  I suspect I applied too much force on the hand drill, which is what broke it.  This granite glass does not set flat well. I put a towel on the board in the water to try to more evenly support it, but it still broke..........


I cut another piece of blue glass, and I applied minimum hand pressure down on the drill. I was able to drill it ok. I used no towel under it, but set it on the piece of 1x12 inch wood in the sink.


Finished 2nd Clock



 3rd Clock

On the 3rd clock, I decided to made the 2nd lamination differently than the front, to increase the strength. I used 2 vertical pieces on the outside, then used a piece for the top where the grain ran horizontally versus vertically.  This made a much stronger frame.

I decided to use yellow and white Kokomo glass for this clock......

 This glass is relatively thick, and it took me a lot of tapping to cut and break it.

Here is the finished clock:





 4th and 5th Glass Clocks

I needed to make some more glass clocks for Christmas gifts to my siblings. I decided to use red oak frames.

I went back to Google Sketchup and modified my design to fit standard 8 inch wide Kokomo glass pieces.  Kokomo Glass cuts their standard pieces to 8 x 16 inches.  I did not realize this when I originally designed the wood frame for the glass clocks, and the original design calls for glass a little narrower than 8 inches.  You can not remove 1/8" of glass using a standard glass cutter.

I made up new cardboard patterns from Google sketchup for making the new clock with standard width 8 inch glass.........


I also decided to make the front lamination with all vertical grain pieces and the back lamination with 2 vertical grain stiles and 1 horizontal grain piece.  When you glue the 2 laminations together, it is much stronger and will not easily break.


I decided to glue up both laminations together, table saw to 8-5/8 width, band saw the outline at least 1/8" wide to allow stock for drum sanding.  The tracing idea on the router did not work well with one lamination thick, because they break too easily. I suppose I could have made a plywood template, temporarily hot glued it, and do the trim router method.  I decided to "brute force" it and just drum sand both laminations glued together.

Here is one clock glued up......

Routing the 1/4" wide and deep groove for the glass:


 I make a cardboard insert simulation of the glass for a couple of reasons:

1. Make a pattern to mark and then cut the glass

2. Find the center of the top arc so I can mark the glass and drill the hole

3. If your wood scraps that you used to make the wood portion yields a smaller
      height clock, the standard glass design will not fit. You need to make a
      custom pattern for the glass

 The process I used to make the cardboard pattern with an arc center mark was:

1. Clamp the wood frame to hold the bottom horizontal piece in place.

2. Set the wood frame upside down onto the cardboard. Mark the inside of the
    wood frame.

3. Mark 3/16" away from bottom horizontal and two verticals and make 3 straight

4. Find the center of the top arc. Draw new arc with 3/16" longer radius.

5. Cut out pattern. Check fit in wood frame.





To find the center, you draw two lines as shown above, pq and rs.  You use the compass to make perpendicular lines. These perpendicular lines cross at the center. The method is illustrated here.


 When I got the 2 new frames done, I noticed my cardboard pattern for the glass was less than 8 inches wide. Standard Kokomo glass sheets are 8 inches wide.  Apparently I made the 2 vertical slides thicker than the 1/2" I wanted.  I ended up changing the bearing on the slot cutter router bit, and routing the grooves about 5/16" versus 1/4" deep. This allowed the 8 inch wide cardboard pattern to fit ok. On the cardboard pattern, I added on 1/4" versus 3/16" on the 2 sides and top to account for this.

 Finished 4th Clock

 I used blue and white Kokomo glass in the 4th turned out to be a beautiful clock.......


This blue glass is Kokomo model number 37.


Stay tuned as I finish the 5th clock........

















**note: the 4 pieces at 3/4" each should have given 3" thickness, but I only got 2.5 inches. Means I lost 1/16" on each of the 8 sides due to planning.

When you order Kokomo glass mail order, you get 8x16".  I designed this clock to accept 8 inch wide glass by random chance (I did not figure in the 8" size of the standard Kokomo glass).  I should probably re-design the wood frame to be slightly bigger to allow some tolerance for the glass fitting into the wood.  You can not easily remove an 1/8 to a 1/4 from the standard 8 inch glass!!



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